x/tools/gopls: deprecate the "allowModfileModifications" setting

[JensSkipr]

What version of Go, VS Code & VS Code Go extension are you using?

Version Information

• Run go version to get version of Go from the VS Code integrated terminal.
  • go version go1.18.7 linux/amd64
• Run gopls -v version to get version of Gopls from the VS Code integrated terminal.
  • golang.org/x/tools/gopls v0.10.1
• Run code -v or code-insiders -v to get version of VS Code or VS Code Insiders.
  • 1.73.0 (8fa188b2b301d36553cbc9ce1b0a146ccb93351f)
• Check your installed extensions to get the version of the VS Code Go extension
  • v0.35.2
• Run Ctrl+Shift+P (Cmd+Shift+P on Mac OS) > Go: Locate Configured Go Tools command.

    GOBIN: undefined
    toolsGopath: /home/skipr/go
    gopath: /home/skipr/go
    GOROOT: /usr/lib/golang
    PATH: /home/skipr/.local/bin:/home/skipr/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/usr/local/go/bin:/home/skipr/go/bin:/usr/local/go/bin:/home/skipr/go/bin
  
    go:    /usr/bin/go: go version go1.18.7 linux/amd64
  
    gotests:    /home/skipr/go/bin/gotests    (version: v1.6.0 built with go: go1.18.2)
    gomodifytags:    /home/skipr/go/bin/gomodifytags    (version: v1.16.0 built with go: go1.18.2)
    impl:    /home/skipr/go/bin/impl    (version: v1.1.0 built with go: go1.18.2)
    goplay:    /home/skipr/go/bin/goplay    (version: v1.0.0 built with go: go1.18.2)
    dlv:    /home/skipr/go/bin/dlv    (version: v1.8.3 built with go: go1.18.2)
    staticcheck:    /home/skipr/go/bin/staticcheck    (version: v0.3.2 built with go: go1.18.2)
    gopls:    /home/skipr/go/bin/gopls    (version: v0.10.1 built with go: go1.18.7)
  
    go env
    Workspace Folder (workspace): /home/skipr/Dev/workspace
    GO111MODULE="auto"
    GOARCH="amd64"
    GOBIN=""
    GOCACHE="/home/skipr/.cache/go-build"
    GOENV="/home/skipr/.config/go/env"
    GOEXE=""
    GOEXPERIMENT=""
    GOFLAGS=""
    GOHOSTARCH="amd64"
    GOHOSTOS="linux"
    GOINSECURE=""
    GOMODCACHE="/home/skipr/go/pkg/mod"
    GONOPROXY=""
    GONOSUMDB=""
    GOOS="linux"
    GOPATH="/home/skipr/go"
    GOPRIVATE=""
    GOPROXY="direct"
    GOROOT="/usr/lib/golang"
    GOSUMDB="off"
    GOTMPDIR=""
    GOTOOLDIR="/usr/lib/golang/pkg/tool/linux_amd64"
    GOVCS=""
    GOVERSION="go1.18.7"
    GCCGO="gccgo"
    GOAMD64="v1"
    AR="ar"
    CC="gcc"
    CXX="g++"
    CGO_ENABLED="1"
    GOMOD="/home/skipr/Dev/workspace/go.mod"
    GOWORK="/home/skipr/Dev/workspace/go.work"
    CGO_CFLAGS="-g -O2"
    CGO_CPPFLAGS=""
    CGO_CXXFLAGS="-g -O2"
    CGO_FFLAGS="-g -O2"
    CGO_LDFLAGS="-g -O2"
    PKG_CONFIG="pkg-config"
    GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3105188839=/tmp/go-build -gno-record-gcc-switches"
  

Share the Go related settings you have added/edited

Run Preferences: Open Settings (JSON) command to open your settings.json file.
Share all the settings with the go. or ["go"] or gopls prefixes.

{
  "go.buildTags": "integration",
  "go.toolsGopath": "~/go",
  "go.toolsManagement.autoUpdate": true,
  "gopls": {
    "build.allowModfileModifications": true
  },
}

Describe the bug

I faced the issue in a large project, but was able to reproduce minimally following: https://go.dev/doc/tutorial/workspaces

Once you add a Golang Workspace by creating a go.work file, every go.mod file returns error: no go.mod file found in /home/skipr/Dev/workspace go list. Where /home/skipr/Dev/workspace is the root of the workspace.

Steps to reproduce the behavior:

1. Start with a blank directory
2. Create a folder hello
3. Start a Go module using go mod init example.com/hello (run inside hello directory)
4. Create hello/main.go containing

package main

func main() {}

5. Start a Go workspace using go work init ./hello (run inside root/workspace directory)
6. Open hello/go.mod

Adding a go.mod to the root doesn't solve the issue. Nor adding . to the go.work. When doing the latter, you even get the same error in the root go.mod:

Screenshots or recordings

See above

[findleyr]

Thanks, I was able to reproduce, but only using "build.allowModfileModifications": true

Disabling that setting should fix your problem, but this is a bug and will be prioritized for the next gopls patch release.

[JensSkipr]

Thanks for the fast response! I tried to remove the option as well, but just realize I only removed it from my workspace config in VS Code, not from my user config. So, it was still active from gopls' point-of-view.

[findleyr]

It was easy to find the bug thanks to your detailed report!

Unfortunately, this is a case where the 'allowModfileModifications' flag has deep implications into the behavior of gopls, and therefore should really be tested against the entire gopls test suite (but isn't).

AFAIK very few people use this setting, and I'd love to deprecate it in favor of go.mod code-lens. Can you share why you have it enabled?

[JensSkipr]

I did some digging and I believe we enabled it when we did bump Go to 1.16. Without this flag, we got following error in VS Code:

Error loading workspace: err: exit status 1: stderr: go: updates to go.sum needed, disabled by -mod=readonly : packages.Load error

Based on your comment, our in-house workflow might not be following best practices. If that's the case, fine for me to remove the flag in our config and move to best practices instead.

I assume above issue could be resolved by doing a go mod tidy.

[findleyr]

I assume above issue could be resolved by doing a go mod tidy.

Thanks for explaining. Yes, that indicates that your workspace is not tidy.

[findleyr]

I think the action to take here is to deprecate the 'allowModfileModifications' setting.

Generally speaking, this setting means "whatever the go command does to your go.mod file is OK". That's not a coherent mode of operation for gopls to support, which is why it has no test coverage. Additionally, the documentation says "this option will eventually be removed".

We should surface the deprecation notice in [email protected], and remove in [email protected].

[gopherbot]

Change https://go.dev/cl/561975 mentions this issue: gopls/internal/settings: deprecate "allowModfileModifications"